Lift truck scale mechanisms



Nov. 6, 1962 w. c. ANDERSON ETAL LIFT TRUCK SCALE MECHANISMS 4Sheets-Sheet 1 Filed May 16, 1958 INVENTORS WIUarL Anderson BY RichardWL fz ATTORAEYS Nov. 6, 19 w. c. ANDERSON ETAL 3,062,308

LIFT TRUCK SCALE MECHANISMS ATTORNEYS Nov. 6, 1962 w. c. ANDERSON ETAL3,062,303

LIFT TRUCK SCALE MECHANISMS Filed May 16. 1958 4 Sheets-Sheet I5INVENTORS W Ca/rl Anderson ATTORNEYS Nov. 6, 1962 w. c. ANDERSON ETAL3,062,308

LIFT TRUCK SCALE MECHANISMS 4 Sheets-Sheet 4 Filed May 16, 1958INVENTORS WILa/rl flzuierson R rd WILozier ATTORNEYS Fig: 14

United States Patent() Canton, Ohio, assignors to The Union MetalManufactoring Company, Canton, Ohio, a corporation of Ohio Filed May 16,1958, Ser. No. 735,830 12 Claims. (Cl. 177-229) Our invention relates toimprovements in lift truck scale mechanisms and more particularly to ascale mechanism which may be positioned between the lifting carriage ofa lift truck and the cantilever type lifting platform thereof, such asbetween the lifting carriage and the forks of a fork lift truck.

A long felt want and need for an eflicient and workable scale mechanismfor lift trucks has been apparent since the advent of the wide spreaduse of lift trucks in modern industry for various material handlingfunctions. Lift trucks, of course, have become an essential part of ourmodern mass production industrial plants for handling various materials,not only in the raw material state, but also in-process materials asWell as finished materials in shipping cartons ready for finaltransportation to the ultimate consumers.

Further, in these modern industrial plants, it has become importantduring many stages of the manufacturing processes, as well as duringfinal shipment, to record the weight of each load of materialtransported by these lift trucks. For example, if the exact weight of aload of substantially identical in-process mass produced parts can berecorded at a given stage of the manufacturing, by knowing the tareweight of the material handling container holding these parts, it ispossible to determine within an extremely low percentage of error thenumber of parts being transported at that particular time, and in thismanner the flow through the mass production lines can be expedited.

Also, it is important to know the weight of a given lot of materialsbeing loaded on outside shipping conveyances, such as commercialshipping trucks, in order to be certain of the total load thesecommercial shipping trucks are carrying. Thus, in order to eliminate thenecessity of the lift truck in each instance carrying each load ofmaterial being moved to a given weighing station having a stationaryweighing scale, it is desirable and long needed to provide a lift truckscale mechanism incorporated directly as a part of a lift truck in orderto automatically and immediately weigh the load of material beingtransported at the time this material is first picked up fortransportation.

Certain prior constructions of lift truck scale mechanisms have beenheretofore provided but none of these have been entirely satisfactoryfor a number of important and vital reasons. One important reason isthat it has not been possible, prior to the present invention, to provie a workable weight indicating device incorporated as a part of such ascale mechanism which will withstand the rugged uses encountered, whilestill providing accurate weight readings without prohibitive maintenanceexpense.

Further, certain of these prior lift truck scale mechanisms have beenconstructed so that increased clearance is necessary between the surfacefrom which the load is to be picked up and the under surface of the mainportion of the material handling container, thereby restricting thevarious types of material handling containers that can be transportedwith a lift truck having the scale mechanism mounted thereon. Stillfurther, since virtually all lift tricks lift and transport theirvarious loads on cantilever type lifting platforms, such as the forks ofa fork lift p, 3,062,308 Patented Nov. 6, -l 962 truck, the further awayfrom the lift truck center of gravity horizontally that the load must becarried by the lift truck the less capacity that a given lift truck has,and certain of these prior left truck scale mechanisms when attached toa lift truck have been of such horizontal dimensions so as to diminishto a prohibitive extent the working capacity of the particular lifttruck.

Finally, another important aspect of lift truck scale mechanisms, againdealing with the requirement that most lift trucks carry their loads ona cantiliver type lifting platform, is that the scale mechanism must beconstructed to eliminate or cancel out all horizontal load componentscreated by this cantilever loading in order to permit an accurateindication of the vertical load components, which vertical loadcomponents are, of course, the actual weight being carried by the lifttruck.

Although certain of these prior constructions have been constructed withvarious members which in theory will provide this elimination orcancelling out of the horizontal load components of the cantilever load,from a practical standpoint and in actual use, these prior members havenot been eflicient nor sufliciently rugged to serve their requiredpurpose.

Thus, in view of the obvious need for a scale mecha nism for lift trucksand the difiiculties with the prior constructions, it is highlydesirable to provide such a scale mechanism which meets all of therequirements of size, convenience, ruggedness and accuracy under longand continued use as outlined.

it is therefore a general object of the present invention to provide alift truck scale mechanism which meets the foregoing requirements andovercomes the difiiculties and disadvantages of the prior constructions.

It is a primary object of the present invention to provide a lift truckscale mechanism which has the necessary accuracy, yet is durable inconstruction and will withstand long and continued rugged use.

It is a further object of the present invention to pro vide a lift truckscale mechanism which may be attached between the lifting carriage andlifting platform of a lift truck, and insures maximum weighing accuracyfor offset or cantilever loads positioned on the lifting platform byaccurately indicating vertical load components produced by the load andeffectively completely eliminating from such indication any horizontalload components of such load.

It is still a further object of the present invention to provide a lifttruck scale mechanism which may be attached between the lifting carriageand lifting platform of a lift truck, yet does not require specialattachment means on either of the litfing carriage or platform.

It is also an object of the present invention to provide a lift truckscale mechanism which includes a unique rugged C-member Weighing meanssupporting the major portion of the vertical load of the lift trucklifting platform and load positioned thereon, such C-member beingconstructed to deflect predetermined and measurable amounts under givenloads.

It is an additional object of the present invention to provide a lifttruck scale mechanism which is constructed to incorporate various safetydevices therein eliminating any danger of the load on the liftingplatform being accidentally released or damaging the scale mechanism dueto an extreme overloading of the scale mechanism.

Finally, it is an object of the present invention to provide a lifttruck scale mechanism which incorporates all of the above advantages,yet is relatively economical to manufacture with a great degree ofaccuracy.

These and other objects are accomplished by the parts, constructions,arrangements, combinations and subcombinations comprising the presentinvention, the naaesasos ture of which is set forth in the followinggeneral statement, a preferred embodiment of whichillustrative of thebest mode of which applicants have contemplated applying theprinciplesis set forth in the following description and illustrated inthe accompanying drawings, and which is particularly and distinctlypointed out and set forth in the appended claims forming a part thereof.

In general terms the lift truck scale mechanism comprising the presentinvention may be stated as including a back plate member, a front platemember, means securing the front and back plate members in spacedsubstantially parallel relation and absorbing and eliminating anyhorizontal load components therebetween, and weight indicating meanssecured to the front and back plate members indicating the greaterportion of any vertical load components therebetween. The back platemember may include preferably hook-like attaching means for attachingthis plate member to the usual lifting carriage of a lift truck, and thefront plate member may include means for receiving the usual preferablyhook-like attaching means of a usual lift truck lifting platform, suchas the forks of a fork lift truck.

Further, the means between the front and back plate members, forabsorbing and eliminating horizontal load components, may include spacedupper and lower, normally horizontally extending, preferably strap-likesupport members with the upper support members normally being tensionmembers and the lower support members being compression members. Also,the weight indicating means between the front and back plate members mayinclude preferably a generally C-shaped deflection member defleetingunder vertical load components and indicator mechanism measuring thedeflection of this C-shaped member and transferring this deflectionmeasurement into weight indications.

Finally, the lift truck scale mechanism comprising the present inventionmay include safety devices attached between the front and back platemembers preferably at the upper support members and at other points formaintaining the scale mechanism assembled in the event of the accidentalfailure of any of the support members. Also, for safety purposes, theweight indicating means C-shaped deflection member may be mountedbetween the front and back plate members so that the deflection of thisC-shaped deflecting member is limited to a safe maximum amount.

By way of example, an embodiment of the lift truck scale mechanism ofthe present invention is illustrated in the accompanying drawingsforming a part hereof, wherein like numerals indicate similar partsthroughout the several views and in which:

FIGURE 1 is a fragmentary side elevation of the scale mechanism of thepresent invention mounted on the lifting carriage of a fork lift truckand having the lifting forks mounted thereon;

FIG. 2, an enlarged fragmentary view taken from FIG. 1 and showing apart of the lift truck lifting carriage, the entire scale mechanism anda part of the lifting forks;

FIG. 3, a back elevation, part in section, of the scale mechanismremoved from the lift truck, looking in the direction of the arrows 33in FIG. 2;

FIG. 4, a front elevation of the scale mechanism with the lift trucklifting forks removed and looking in the direction of the arrows 44 inFIG. 2;

FIG. 5, a vertical sectional view, part in elevation, looking in thedirection of the arrows 55 in FIG. 4;

FIG. 6, a fragmentary sectional view, part in elevation, looking in thedirection of the arrows 6--6 in FIG. 4;

FIG. 7, a fragmentary sectional view, part in elevation, looking in thedirection of the arrows 7-7 in FIG. 4;

FIG. 8, a fragmentary sectional view, part in elevation, looking in thedirection of the arrows 3-8 in FIG. 5;

FIG. 9, a fragmentary sectional view, part in elevation, looking in thedirection of the arrows 99 in FIG. 5;

FIG. 10, a fragmentary back elevation of the weight indicating device;

FIG. 11, a. sectional view, part in elevation, looking in the directionof the arrows 11-11 in FIG. 10;

FIG. 12, a sectional view, part in elevation, looking in the directionof the arrows 12-12 in FIG. 10;

FIG. 13, a fragmentary sectional View, part in elevation, looking in thedirection of the arrows 1313 in FIG. 12; and

FIG. 14, a fragmentary sectional view, part in elevation, looking in thedirection of the arrows 1414 in FIG. 12.

As illustrated in FIGS. 1 and 2 of the drawings, the particularembodiment of the lift truck scale mechanism comprising the presentinvention is shown in combination with a particular form of fork lifttruck. It should be understood, however, that the principles of thepresent invention are not limited to the particular fork lift truckshown nor to fork lift trucks in general. Obviously, with minor changesfrom the embodiment of the scale mechanism illustrated, this scalemechanism may be easily adapted for use with virtually any form ofmaterial handling truck and for many other load sensing applications andsuch changes are contemplated within the scope of the present invention.Thus, where the terms vertical and horizontal are used in the following,it should be understood that these terms could be used interchangeablywith longitudinal and lateral respectively.

Referring to FIGS. 1 and 2, a lift truck, generally in dicated at 20,having the usual mast 21, is provided with the usual vertically movablelifting carriage 22, which carriage includes the upper and lower liftingbars 23 and 24. The scale mechanism of the present invention isgenerally indicated at 25, being attached to the lifting bars 23 and 24and having the usual lifting forks 26 attached thereto.

The scale mechanism 25 includes the back plate member 27, the frontplate member 23, the upper supporting members 29, the lower supportingmembers 30 and a weight indicating means, generally indicated at 31. Theback plate member 27, as best seen in FIGS. 2 and 3, is provided withthe spaced cut-outs 32 formed in the upper edge 33 and the spacedcut-outs 34 formed in the lower edge 35, these cut-outs being formed fora purpose to be herein after more fully described.

Further, a hook member 36 is attached by means of the spaced bolts 37 tothe back plate member upper edge 33 and extending the entire Width ofthis plate member. Also, a hook member 38 is attached centrally of theback plate member 27 at the lower edge 35 by means of a pair of bolts39. Both of these hook members 36 and 38 extend rearwardly and arepositioned to engage the lift truck lifting carriage 22 after thelifting forks 26 have been removed, with the hook member 36 engagingover the upper lifting bar 23 and the hook member 38 engaging under thelower lifting bar 24, thereby retaining the scale mechanism 25 securelyon the lift truck lifting carriage 22 in lieu of the lifting forks 26.

Still further, the back plate member 27 is provided with a generallyU-shaped cut-out 40 in the side edge 41 and a similar generally U-shapedcut-out 42 in the side edge 43, again for a purpose to be hereinafterdescribed.

The front plate member 28, as seen in FIGS. 2 and 4, likewise isprovided with the spaced cut-outs 44 in the upper edge 45, with thelower extremities of these cut-outs 44 normally being horizontallyaligned with the lower extremities of the back plate cut-outs 32. Again,similar to the back plate member, the front plate member 28 is providedwith the spaced cut-outs 46 in the lower edge 47 having the upperextremities thereof normally horizontally aligned with the upperextremities of the back plate cutouts 34.

Still further, the front paate member 28 is provided with the generallyU-shaped cut-out 48 in the side edge 49, similar to and normally alignedwith the cut-outs 40 in the back plate side edge 41, for a purpose to behereinafter described.

Back and front plate members 27 and 23 are positioned in generallyvertically extending, spaced, substantially parallel relationship, andare retained in such relationship despite slight vertical movement ofthe front plate member 28 with reference to the back plate member 27 bythe upper and lower supporting members 29 and 36 and the weightindicating means, generally indicated at 31. The upper and lowersupporting members 29 and 39 are preferably formed from heat treatedspring steel and, although the upper and lower members differ somewhatin configuration, both upper and lower sets are somewhat strap-like inoverall configuration.

The upper supporting members 29 are formed with thickened end portions50, and relatively thin center portions 51 extending between these endportions, with the overall widths of these members being substantiallyuniform throughout the thickened end and thinner center portions, asbest seen in FIG. 6. The lower supporting members 30 are also formedwith thickened end portions 52, but are provided with relatively thinintermediate portions 53 adjacent the thickened end portions 52, andthickened center portions 54. Again, the widths of these lowersupporting members also are substantially uniform throughout the extentof portions 52, 53 and 54, as best seen in FIG. 7.

The upper supporting members 28 are positioned in double thicknessstacks with the end portions 5t thereof received in the back plate uppercut-outs 32 and the front plate upper cut-outs 44. Further, these endportions are secured to the back plate member 27 by a series of bolts 55and to the front plate member by a series of bolts 56, with the centerportions of these upper supporting members extending generallyhorizontally between plate members 27 and 28.

The lower supporting members are likewise positioned with their endportions 52 received in the back plate lower cut-outs 34 and front platelower cut-outs 46. Also, these end portions are secured to the backplate member by means of a series of bolts 57 and to the front platemember by a series of bolts 58, with the thinner intermediate portions53 coinciding with the back plate front face 59 and the front plate backface 60. Finally, the lower supporting member center portions 54 extendgenerally horizontally between the intermediate portions 53 and platemembers 27 and 28, and these lower supporting member center portions 54are at all times substantially parallel to the upper supporting membercenter portions 51.

The particular configurations of these upper and lower supportingmembers 2? and 30 are designed to give these supporting members maximumflexibility while still serving their particular supporting functions.As will be more clearly seen at the complettion of the description, thespecific purpose of the upper supporting members 29 is to withstand andabsorb forces between the plate members 27 and 28 tending to separatethe upper portions of these plate members, thereby placing these uppersupporting members in tension.

Further, the purpose of the lower supporting members '30 is to resistand absorb forces tending to move the lower portions of the platemembers 27 and 28 together, thereby placing these lower supportingmembers in compression. Such tension and compressive forces are createdby a cantilever load being placed on the lift truck lifting forks 26 andit is for this reason that it is important that these upper and lowersupporting members 29 and 3% always remain substantially parallel andthat the supporting members have as great a flexibility as possiblewhile still serv- 6 ing their tension and compression purposes, so asnot to create any more resistance to the vertical movement of the frontplate member 28 with respect to the back plate member 27 than isnecessary, both of these points of construction to be hereinafterexplained more clearly in detail.

As best seen in FIGS. 4 and 9, the front plate member upper cut-outs 44are covered by the recessed engagement bars 61, the upper surfaces ofwhich are aligned with the front plate upper edge 45 and the lowersurfaces of which are spaced above the upper ends of the supportingmember bolts 56. Likewise, the front plate lower cutouts 46 are coveredby the recessed engagement bars 62, with these bars having their lowersurfaces aligned with the front plate lower edge 47 and their uppersurfaces spaced downwardly from the lower ends of the engagement memberbolts 58.

The purpose of these front plate engagement bars 61 and 62 is to providea continuous upper and lower edge on the front plate member 28 forengagement by the lifting forks 26. Each of the lifting forks 26 is ofthe usual L-shaped configuration and is provided on its upright portionwith the usual upper engagement hooks 63 and the lower engagement hook64, which hooks, when the scale mechanism of the present invention isnot used, would normally engage the upper lifting bar 23 and lowerliftin g bar 24, respectively, of the lift truck lifting carriage 22.

With the provision of the scale mechanism of the present invention,however, these fork hooks 63 and 64 engage over the front plate upperedge 45 and lower edge 47, respectively, as shown in FIGS. 1 and 2.Also, in usual construction as shown in FIG. 2, the fork upper hooks 63are provided with the spring loaded pins 65, which pins partially engagein the rear surface of the member on which these hooks 25 are mounted inorder to retain the hooks properly laterally spaced as desired.

Thus, for the purpose of receiving the spring loaded pins 65, the frontplate upper engagement bars 61 are provided with a series of spaced halfholes 66 at the back surfaces 67 of these bars, and these half holescontinue and are formed in the front plate back face 60, as best seen inFIG. 9. With this construction, therefore, lifting forks 26 are mountedon the front plate member 28 with the upper hooks 63 engaged over theupper edge 45 or the engagement bars 61 and with the spring loaded pins65 engaged in certain of the half holes 66. At the same time the forklower hooks 64 are engaged over the front plate lower edge 47 or theengagement bars 62.

The weight indicating means, generally indicated at 31, includes theC-shaped spring-like deflection member 68 and the indicator mechanism69. The deflection member 68 has the C-shaped spring portion 70, theupper exten sion arm 71 and the lower extension arm 72, with the springportion 70 having an upper horizontal leg 73, a lower horizontal leg 74and a vertical leg 75 extending vertically between legs 73 and 74, asbest seen in FIG. 8.

As can be clearly seen in FIGS. 2 through 5 and 8, the deflection member68 is telescoped between the front and back plate members 27 and 28,with the upper horizontal leg 73 of the spring portion 70 secured to theback plate member 27 through the upper clevis 76, and the lowerhorizontal leg '74 of spring portion 70 secured to the front platemember 28 through the lower clevis 77. The upper and lower clevises 76and 77 are similar in shape, being generally U-shaped in cross section,as shown in FIG. 5, and having generally circular outer configurations.

The upper clevis 76 is telescoped downwardly over the spring portionupper horizontal leg 73 and is secured to this spring portion leg bymeans of a bolt 78, which bolt passes through the spring portion leg 73substantially laterally midway or at least intermediate of the length ofthe leg 73 spaced from the vertical leg 75 and substantially laterallymidway of the front and back plate members 27 and 28. Furthermore theends of bolt 78 extend into the clearance openings 79 and 80 in thefront and back plate members respectively.

The upper clevis 76 is retained in the circular recess 81 formed in theback plate front face 59 by a series of bolts 82, and also this clevisis received in the clearance recess 83 formed in the front plate backface 60, as shown. It is important that the recess 83 provides apredetermined clearance around all portions of the clevis 75 whichprotrude into this recess, which clearance, coupled with the clearancearound the bolt 78 provided by the clearance opening 79, permits limitedvertical movement of the front plate member 28 with reference to theback plate member 27 and clevis 76.

The lower clevis 77 is similarly secured to the spring portion lowerhorizontal leg 74 by a bolt 84 with the ends of bolt 84 likewiseextending into the clearance openings 85 and 86 in the front and backplate members. Also, lower clevis 77 is retained on the front platemember 23 in a circular recess 87 by means of a series of bolts 28 andis received in the back plate clearance recess 89.

Again, the clearance recess 89 provides a limited clearance completelyaround the portion of the lower clevis 77 which extends into the backplate member 27, with the clearance of this recess combined with theclearance opening 86, permitting limited vertical movement of the frontplate member 28 and lower clevis 77 with respect to the back platemember 27. Thus, since the Spring portion upper horizontal leg '73 issecured to the back plate member 27 and the spring portion lowerhorizontal leg 74 is secured to the front plate member, the front platemember is permitted to move vertically with respect to the back platemember by a sufiicient vertical load being placed on the front platemember 28 to deflect the spring portion 70, such vertical movement beingpermitted within the limitations of the clearance between the clearancerecesses 83 and 89 and the outer extremities of the upper and lowerclevises 76 and 77.

Furthermore, as can be clearly seen in FIGS. and 8, the Spring portion70 can be easily and evenly deflected by such vertical load due to thebolts 78 and 84 being cylindrical, as shown, and being received throughcylindrical holes, as shown, in the upper and lower horizontal legs 73and 74 of spring portion 70, to thereby provide pivotal connectionsbetween spring portion 713 and the plate members 27 and 28. Also, thedeflection of the spring portion 79 is permitted by the fact that thepivotal connections between the spring portion legs 73 and 74, and theplate members 27 and 28 are at locations intermediate the horizontallengths of legs 73 and 74, spaced from the spring portion vertical leg75.

The upper and lower extension arms 71 and 72 are both preferablygenerally L-shaped in cross section, as shown in FIG. 11, with the upperextension arm 71 being secured to the spring portion upper horizontalleg 73 and extending generally horizontally to the indicator mechanism69, as shown in FIG. 8. Further this upper extension arm 71 extendsdownwardly adjacent the indicator mechanism case 90 and is secured tocase 91} through a block 91, as shown.

The lower extension arm 72 is secured to the spring portion lowerhorizontal leg 74 and likewise extends horizontally to the indicatormechanism case 90. At the end of the lower extension arm 72, adjacentthe case 90, is mounted a vertically adjustable platform member 92 whichabuts a vertically movable pin 93 protruding downwardly from andvertically movable with respect to the case 90.

As shown in detail in FIGS. through 14, pin 93 is resiliently retainedin abutting relation with the lower extension arm platform member 92 bymeans of the spring 94 and this pin in turn engages over one end of apivotal beam member 95 through a knife edge 96. Beam member 95 ispivotally attached to the case 90 through a pivot pin 97 mounted in alaterally adjustable block 98.

Block 93 is threadably engaged with an adjusting screw 99, whichadjusting screw is in turn received in a portion of case 99 androtatable with respect to this case. Thus by a selective adjustment ofthe adjusting screw 99, block 98 may be moved to, in effect, change thepivot point of beam member 95 with respect to the remaining mechanism ofthe indicator mechanism 69, to thereby adjust and calibrate thisindicator mechanism as required.

The end of beam member 95 opposite from the pin 93 is in turn engagedwith a second vertically movable pin 10% through another knife edge 101.Finally, the pin 10% is secured to a vertical gear rack 102 which is inturn operably connected through a series of gearing, generally indicatedat 193, to a usual rotatable revolutions counter 194 and dial indicatorpointer 105, both the counter and pointer being shown in FIG. 3 andbeing contained within a dial indicator case 106.

The dial indicator case 106 may have the usual rotatable non-breakableglass face having the weight indications printed thereon. Further thiscase may be provided with the usual tare adjustment 107.

Thus, with the scale mechanism described, when a given load is picked upor placed on the lifting forks 26, this will create a downward verticalforce on front plate member 28, which causes the spring portion 7t? todeflect a predetermined amount, permitting the front plate member 28 tomove a slight distance downwardly with reference to the back platemember 27. This deflection of the spring portion 70 causes the upper andlower extension arms '71 and 72 to move a slightly greater distanceapart and, through the various mechanisms of the indicator mechanism 69,the deflection of the spring portion 7% is transmitted into a weightindication by the dial indicator pointer and revolutions counter 10Still further, this downward movement of the front plate member 28 withrespect to the back plate member 27 is permitted by the upper and lowersupporting members 29 and 30, while these supporting members maintainplate members 27 and 28 in proper spaced alignment. Finally, since theupper supporting members 29 are substantially parallel to the lowersupporting members 30, these supporting members absorb and cancel outthe turning moment placed on the front plate member 28 by the offset orcantilever load on the lifting forks 26.

As before described, the upper supporting members 29 are placed intension by this turning moment and the lower supporting members 34 areplaced in compression, with both sets of supporting members being formedsufficiently strong to resist the forces created therein by this turningmoment while at the same time being sufliciently flexible so as tocreate as little resistance as possible to the vertical movement of theplate member 28. Also, due to the particular construction of the lowersupporting member 30, as hereinbefore described, these lower supportingmembers are sufficiently strong in column strength or resistance tobuckling for resisting and absorbing the horizontal load componentsurging the lower portions of the plate members 27 and 28 together, whilestill maintaining the foregoing vertical flexibility. Furthermore,because the upper and lower supporting members 29 and 30 extend in ageneral horizontal direction between the plate members 27 and 28 andbecause the total possible vertical movement of the front plate member28 with reference to the back plate member 27 is sufficiently small,these supporting members can never be deflected sufficiently near avertical position so as to transmit more than a small amount of thevertical load components between the plate members.

As shown particularly in FIGS. 1, 3 and 5, the case of the indicatormechanism 69 extends rearwardly through the generally U-shaped cut-out40 formed in the side edge 41 of the back plate member 27, so that thisindicator mechanism can be conveniently observed by the operator of thelift truck 20. Furthermore, because of the generally U-shaped cut-out 42in the back plate side edge 43 and the generally U-shaped cut-out 48 inthe front plate side edge 49, the operator of the lift truck 20 mayconveniently observe the location of the lifting forks 26 so that thelift truck opcrators vision is not obscured by this scale mechanismduring the operation of picking up a load.

For maximum safety in the use of the scale mechanism comprising thepresent invention, certain safety features are inherently built into themechanism and others are preferably included. First, as beforedescribed, the upper clevis 76 secured to the back plate 27 is receivedin the clearance recess 83 of the front plate member 28 and the lowerclevis 77 secured to the front plate member 23 is received in theclearance recess 89 of the back plate member 27.

Thus, the downward movement of front plate member 28 with reference toback plate member 27 is limited by the clearance between these clevisesand their respective clearance recesses. Furthermore, this clearance iscalculated to be less than the deflection that would. damage or causethe deflection member 68 to fail. In this manner, it is assured that,even though a load beyond the capacity of the scale mechanism is placedon the lifting forks 26, the deflection member 68 will not fail, sincethe total deflection thereof will be limited to a safe amount.

A second safety feature is preferably provided in the scale mechanismcomprising the present invention by the safety plates 108, shown inFIGS. 1 through 6, 8 and 9 of the drawings. As shown, safety plates 108are positioned resting 'on and covering the upper supporting members 29,also extending between the back and front plate members 27 and 28 andbeneath the front plate member engagement bars 61.

Safety plates 108 are provided with a series of openings 109, whichopenings coincide with and receive the upper ends of the back plateengagement member bolts 55 and the front plate engagement member bolts56, as best seen in FIG. 6. Furthermore, the plate openings 109 aresufficiently larger than the upper ends of the bolts 55 and 56 toprovide clearance allowing the necessary vertical movement of frontplate member 28 with reference to back plate member 27 and also toprovide clearance so that no horizontal or vertical load components willbe in any way absorbed or affected by these plates 108.

Thus, safety plates 108 are constructed so that, under normal operationof the scale mechanism of the present invention, this scale mechanismwill properly function as if these safety plates were not present, butif through accident, the scale mechanism is overloaded to an extremeextent sufficient to cause horizontal load components beyond the tensilecapacity of the upper supporting members 29 and causing these supportingmembers to fail, the safety plates 108 through engagement with the upperends of the bolts 55 and 56 will prevent extreme horizontal separationof the back and front plate members 27 and 28 which could cause damageto the deflection member 68. Also, these safety plates 108 serve as aprotection covering for guarding the upper supporting members 29 frombeing damaged by objects falling downwardly between the plate members 27and 28 from above.

Finally, another safety feature which is preferably incorporated in thescale mechanism of the present invention is provded by the safety links110, shown in FIGS. 1 through 4, 8 and 9. These safety links 110 arepreferably positioned inset in the back plate side edges 41 and 43 andthe front plate side edges 49 and 111, extending between the back andfront plate members 27 and 28, as shown.

Further, safety links 110 are pivotally connected to the plate members27 and 28, permitting free vertical movement between these plate membersto the necessary extent for the proper function of the scale mechanismAgain, however, in the event of the excessive overloading of the scalemechanism causing the failure of the upper supporting members 29, thesafety links 110 will prevent further horizontal separation of platemembers 27 and 28 and thereby prevent damage to the deflection member68.

The most ideal lift truck scale mechanism construction, according to theforegoing description and shown in the drawings, would have upper andlower supporting members 29 and 30 between the back and front platemembers 27 and 28 having sufficient flexibility so that absolutely freelimited vertical movement is permitted between the back and front platemembers when a load, within the capacity of the mechanism, is placed onthe cantilevertype lifting forks 26. As a practical matter, however, inorder to provide this scale mechanism of sufficient capacity andruggedness for use with lift trucks in modern manufacturing plants, ithas been found that these most ideal conditions cannot be met, butrather, in order to properly support the back and front plate members 27and 28 and maintain these plate members properly spaced, it is necessaryto sacrifice flexibility of the supporting members 29 and 30 to providethese supporting members with sufiicient tensile and compressivestrength and stiffness.

Thus, it has been found, when the upper and lower supporting members 29and 30 are formed of suflicient strength to withstand the loads andabuse encountered, that these supporting members will actually absorb acertain percentage of the vertical load components to which the platemembers 27 and 28 are subjected by a load being placed on thecantilever-type lifting forks 26. It has further been found that thepercentage of vertical load components absorbed might be as high asapproximately 15% of the total vertical load components created by theload on the forks.

These vertical load components absorbed in a particular assembly of thescale mechanism by these supporting members 29 and 3d are, however,measurable, and they vary at a uniform rate for an increase or decreasein load on the lifting forks. Thus, the vertical load componentsabsorbed by the supporting members 29 and 30 may be simply and easilycompensated for by an adjustment in the indicator mechanism 69.

For this reason, referring particularly to FIGS. 12 and 13 ashereinbefore described, it is merely necessary to adjust the adjustingscrew 99, thereby moving block 98 to change the pivot point of the beammember with respect to the remaining mechanism of the indicatormechanism, and thereby adjust and calibrate this indicator mechanism soas to compensate for the percentage of the vertical load componentswhich are actually being absorbed by the supporting members 29 and 30.In this manner, the indicator mechanism 69 can be adjusted to give atrue reading of the actual vertical load components imparted by the loadon the lifting forks.

The percentage of vertical load components which will be absorbed by theupper and lower supporting members 29 and 30 will, of course, varydepending on the particular form of these supporting members. Forinstance, with the lower supporting members 30 being constructed withthe relatively short and thin portions 53 and thickened center portions54, thereby providing these members with increased flexibility whilemaintaining column strength, less vertical load components will beabsorbed by these lower supporting members than if these members wereformed with a continuous cross section, such as that of the thickenedcenter portions 54.

Although the lower supporting members 30 have been shown having shortintermediate portions 53 of a decreased vertical thickness from thethickened center portions 54, it should be understood that increasedflexibility for these supporting members can be provided by decreasingthe thickness of the relatively short intermediate portions 53 in eithera horizontal or vertical direction or both, so that when theintermediate portions 53 are referred to as thin, it is intended thatthis thinness may be in'any direction so that these intermediateportions 53 have aeeasos if a less cross sectional area than thethickened center portions 54.

A further important aspect of the scale mechanism comprising the presentinvention is the provision of the generally C-shaped deflection member63 including the C-shaped spring portion 70. As before described, theupper horizontal leg 73 of spring portion 70 is secured to the backplate member 27 through the upper clevis 76 and the lower horizontal leg74 of spring portion 70 is secured to the front plate member 28 throughthe lower clevis 77, so that the vertical load components of the load onthe lifting forks 26 are transferred into deflection of spring portion 70, which deflection, through the upper end lower extension arms 71 and72, is directly measured and transferred into weight indications by theindicator mechanism 69.

Thus, through the combination of the upper and lower supporting members29 and 3t and the deflection member 68, all horizontal load componentscreated by the cantilever loading are for all practical purposescompletely cancelled out and eliminated, while the greater portion ofthe vertical load components is accurately transferred into a form, thatis, a deflection, which can be accurately measured and indicated asweight indications. Further, this is done by rugged supporting membersand 3i) and a rugged deflection member 68, none of which, within theirvarious capacities, are subject to any extreme wear and all of which arecapable of withstanding the rugged uses encountered by lift truck scalemechanisms, while still properly and accurately serving their requiredpurposes.

Another important advantage which may be included in the scale mechanismof the present invention is the safety feature which prevents damage toand even possible failure under extreme overloading conditions of thedeflection member 63, both by the failure of the upper supportingmembers 29 or merely by a deflection of member 6d beyond its capacity.As before described, in the event of failure of the upper supportingmembers 29, the safety plates 1&8 and safety links llltl will preventexcessive sepal ration of the upper portions of the front and back piatemembers 27 and 28 which otherwise could result in damage to thedeflection member 63.

Further the particular mounting of the upper and lower clevises 76 and77 received in the front plate clearance recess 83 and back plateclearance recess 89, respectively, limits the extent to which thedeflection member 68 can be deflected, and if an overload isencountered, these clevises 76 and 77 will engage the plate memberspreventing the deflection of the deflection member 68 to an extent whichcould possibly damage this member. Also, all of these safety featuresmay be provided without affecting the accuracy of the scale mechanismcomprising the present invention Within the predetermined capacity ofthis scale mechanism.

Finally, another feature, which is provided by the embodiment of thescale mechanism of the present invention shown, is that this scalemechanism may be mounted on a lift truck between the lifting carriageand lifting platform or forks without the necessity of providing specialfastening means and without moving the lifting platform or forks of thelift truck a prohibitive horizontal distance from the center of gravityof the truck. As illustrated and described, the hook members 36 and 38may be conveniently engaged with the lifting bars 23 and 24 of the lifttruck lifting carriage 22 and the engagement hooks 63 and 64 of the lifttruck lifting forks may be conveniently engaged with the scale mechanismfront plate member 28.

In the foregoing description, certain terms have been used for brevity,clearness and understanding, but no unnecessary limitations are to beimplied therefrom, because such words are used for descriptive purposesherein and are intended to be broadly construed.

Moreover, the embodiment of the improved construction illustrated anddescribed herein is by way of example 12 and the scope of the presentinvention is not limited to the exact details of construction shown.

Having now described the invention, the construction, operation and useof a preferred embodiment thereof, and the advantageous, new and usefulresults obtained there by; the new and useful construction andreasonable mechanical equivalents thereof obvious to those skilled inthe art are set forth in the appended claims.

We claim:

1. Scale mechanism including a first generally longitudinal suspensionmember, a second generally longitudinal suspension member spacedlaterally from the first member, the first and second members havinglongitudinally spaced portions, load receiving means operably connectedto the second member for receiving a longitudinally applied load,support means operably connected between the longitudinally spacedportions of the first and second members generally flexible for relativelongitudinal movement between said first and second members andgenerally rigid for absorbing and cancelling out substantially alllateral load components imparted between said first and second membersby said longitudinally applied load on said load receiving means, saidsupport means longitudinal flexibility providing said support meansincapable of absorbing at least the greater portion of any longitudinalload components to which the first and second members are subjected bysaid load on said load receiving means, at least certain of said supportmeans being placed in tension by said load on said load receiving means,safety means between the first and second members operably connectednormally free of tension and normally freely longitudinally pivotal fornormal free relative longitudinal movement between said first and secondmembers, said safety means being substantially rigid in tension forresisting separation of said first and second members in the event offailure of said support means placed in tension, said safety means beingnormally freely longitudinally pivotal and therefore normallysubstantially incapable of absorbing any longitudinal load components towhich said first and second members are subjected by said load on saidload receiving means, and weight indicating means operably connected tothe first and second members for absorbing at least the greater portionof all longitudinal load components to which said first and secondmembers are subjected by said load on said load receiving means.

2. Scale mechanism including a first generally longitudinal suspensionmember, a second generally longitudinal suspension member spacedlaterally from the first member, load receiving means operably connectedto the second member for receiving a longitudinally applied load,support means operably connected between the first and second membersgenerally flexible for relative longitudinal movement between said firstand second members and generally rigid for absorbing and cancelling outsubstantially all lateral load components imparted between said firstand second members by said longitudinally applied load on said loadreceiving means, said support means longitudinal flexibility providingsaid support means incapable of absorbing at least the greater portionof any longitudinal load components to which said first and secondmembers are subjected by said load on said load receiving means, adeflection member having longitudinally spaced laterally extending legportions joined by a longitudinally extending connecting portion ingenerally C-shape positioned between the first and second suspensionmembers, first connection means mounted extending laterally between oneof said deflection member spaced leg portions and said first suspensionmember pivotally connecting said one leg portion to said firstsuspension member, second connection means mounted extending laterallybetween the other of said deflection member spaced leg portions and saidsecond suspension member pivotally connecting said other leg portion tosaid second suspension member, the first and second connection meansbeing operably connected to the respective deflection member spaced legportions at locations laterally spaced from said deflection memberlongitudinally extending connecting portion, the deflection memberabsorbing at least the greater portion of all longitudinal loadcomponents to which the first and second members are subjected by saidload on said load receiving means and the absorption of the longitudinalload components causing deflection of at least one of said deflectionmember leg portions, and means operably connected to the deflectionmember for indicating the deflection between the leg portions thereof.

3. The scale mechanism as defined in claim 2 in which there is means onat least one of the first and second suspension members operablypositioned relative to the deflection member leg portions for limitingthe deflection of the deflection member leg portions to a predeterminedmaximum deflection resulting from a load on the load receiving means.

4. The scale mechanism as defined in claim 3 in which the means forlimiting deflection of the deflection member leg portions resulting froma load on the load receiving means includes a recess formed in the firstsuspension member having predetermined longitudinal limits in bothlongitudinal directions and being laterally aligned with the secondconnection means connecting a deflection member leg portion to thesecond suspension member, and a recess formed in the second suspensionmember having predetermined longitudinal limits in both longitudinaldirections and being laterally aligned with the first connection meansconnecting a deflection member leg portion to the first suspensionmember; in which each of the connection means of the deflection memberleg portions extends partially laterally into the respective laterallyaligned recess; and in which the predetermined longitudinal limits ofeach of the recesses provide a predetermined clearance for therespective connection means partially received therein in bothlongitudinal directions to provide clearance for the predeterminedmaximum deflection of the deflection member leg portions resulting froma load on the load receiving means.

5. The scale mechanism as defined in claim 4 in which the meansindicating the deflection of the deflection member leg portions includesan extension arm mounted on each of said leg portions, and means forindicating the deflection of said extension arms; and in which each ofthe first and second connection means of the deflection member legportions is a generally U-shaped cross-section longitudinally openclevis secured to the respective first and second suspension members andpivotally connected to the respective deflection member leg portions.

6. Scale mechanism including a first generally longitudinal suspensionmember, a second generally longitudinal suspension member spacedlaterally from the first member, the first and second members havinglongitudinally spaced portions, load receiving means operably connectedto the second member for receiving a longitudinally applied load,generally lateral substantially parallel strap-like support meansoperably connected between the longitudinally spaced portions of thefirst and second members generally flexible for relative longitudinalmovement between first and second members and generally rigid forabsorbing and cancelling out substantially all lateral load componentsimparted between said first and second members by said longitudinallyapplied load on said load receiving means, said support meanslongitudinal flexibility providing said support means incapable ofabsorbing at least the greater portion of any longitudinal loadcomponents to which said first and second members are subjected by saidload on said load receiving means, at least certain of said supportmeans being placed in compression by said load on said load receivingmeans, the first and second members having laterally opposed 1d innerfaces at said support means placed in compression, said support meansplaced in compression having relatively short thin flexible sectionsadjacent said first and second member inner faces and having sections ofincreased thickness the remainder of and the major portion of thelateral space between said first and second members, a deflection memberhaving longitudinally spaced laterally extending leg portions joined bya longitudinally extending connecting portion in generally C-shapepositioned between the first and second suspension members, firstconnection means mounted extending laterally between one of saiddeflection member spaced leg portions and said first suspension memberpivotally connecting said one leg portion to said first suspensionmember, second connection means mounted extending laterally between theother of said deflection member spaced leg portions and said secondsuspension member pivotally connecting said other leg portion to saidsecond suspension member, the first and second connection means beingoperably connected to the respective deflection member spaced legportions at locations laterally spaced from said deflection memberlongitudinally extending connecting portion, the deflection memberabsorbing at least the greater portion of all longitudinal loadcomponents to which the first and second members are subjected by saidload on said load receiving means and the absorption of the longitudinalload components causing deflection of at least one of said deflectionmember leg portions, and means operably connected to the deflectionmember for indicating the deflection between the leg portions thereof.

7. The scale mechanism as defined in claim 6 in which there is means onat least one of the first and second suspension members operablypositioned relative to the deflection member leg portions for limitingthe deflection of the deflection member leg portions to a predeterminedmaximum deflection resulting from a load on the load receiving means.

8. The scale mechanism as defined in claim 7 in which at least certainof the support means are placed in tension by said load on said loadreceiving means; in which safety means is positioned between the firstand second suspension members operably connected normally free oftension and normally freely longitudinally pivotal for normal freerelative longitudinal movement between said first and second members,said safety means being substantially rigid in tension for resistingseparation of said first and second members in the event of failure ofsaid support means placed in tension; and in which said safety means isnormally freely longitudinally pivotal and therefore normallysubstantially incapable of absorbing any longitudinal load components towhich said first and second members are subjected by said load on saidload receiving means.

9. The scale mechanism as defined in claim 7 in which the means forlimiting deflection of the deflection member leg portions resulting froma load on the load receiving means includes a recess formed in the firstsuspension member having predetermined longitudinal limits in bothlongitudinal directions and being laterally aligned with the secondconnection means connecting a deflection member leg portion to thesecond suspension member, and a recess formed in the second suspensionmember having predetermined longitudinal limits in both longitudinaldirections and being laterally aligned with the first connection meansconnecting a deflection member leg portion to the first suspensionmember; in which each of the connection means of the deflection memberleg portions extends partially laterally into the respective laterallyaligned recess; and in which the predetermined longitudinal limits ofeach of the recesses provide a predetermined clearance for therespective connection means partially received therein in bothlongitudinal directions to provide clearance for the predeterminedmaximum deflection of the deflection member leg portions resulting froma load on the load receiving means.

10. Scale mechanism including a first generally longitudinal suspensionmember, a second generally longitudinal suspension member spacedlaterally from the first member, the first and second members havinglongitudiually spaced portions, load receiving means operably connectedto the second member for receiving a longitudinally applied load,support means operably connected between the longitudinally spacedportions of the first and second members generally flexible for relativelongitudinal movement between said first and second members andgenerally rigid for absorbing and cancelling out substantially alllateral load components imparted between said first and second membersby said longitudinally applied load on said load receiving means, saidsupport means longitudinal flexibility providing said support meansincapable of absorbing at least the greater portion of any longitudinalload components to which the first and second members are subjected bysaid load on said load receiving means, at least certain of said supportmeans being placed in tension by said load on said load receiving means,safety means between the first and second members operably connectednormally free of tension and normally freely longitudinally pivotal fornormal free relative longitudinal movement between said first and secondmembers, said safety means being substantially rigid in tension forresisting separation of said first and second members in the event offailure of said support means placed in tension, said safety means beingnormally freely longitudinally pivotal and therefore normallysubstantially incapable of absorbing any longitudinal load components towhich said first and second members are subjected by said load on saidload receiving means, a deflection member having longitudinally spacedlaterally extending leg portions joined by a longitudinally extendingconnecting portion in generally C-shape positioned between the first andsecond suspension members, first connection means mounted extendinlaterally between one of said deflection member spaced leg portions andsaid first suspension member pivotally connecting said one leg portionto said first suspension member, second connection means mountedextending laterally be tween the other of said deflection member spacedleg portions and said second suspension member pivotally connecting saidother leg portion to said second suspension member, the first and secondconnection means being operably connected to the respective deflectionmember spaced leg portions at locations laterally spaced from saiddeflection member longitudinally extending connecting portion, thedeflection member absorbing at least the greater portion of alllongitudinal load components to which the first and second members aresubjected by said load on said load receiving means and the absorptionof the longitudinal load components causing deflection of at least oneof said deflection member leg portions, means on at least one of thefirst and second suspension members operably positioned relative to thedeflection member leg portions for limiting the deflection of thedeflection member leg portions to a predetermined maximum deflectionresulting from a load on the load receiving means, and means operablyconnected to the deflection member for indicating the deflection betweenthe leg portions thereof.

11. The scale mechanism as defined in claim 10 in which the means forlimiting deflection of the deflection member leg portions resulting froma load on the load receiving means includes a recess formed in the firstsuspension member having predetermined longitudinal limits in bothlongitudinal directions and being laterally aligned with the secondconnection means connecting a deflection member leg portion to thesecond suspension member, and a recess formed in the second suspensionmember having predetermined longitudinal limits in both longitudinaldirections and being laterally aligned with the first connection meansconnecting a deflection memher leg portion to the first suspensionmember; in which each of the connection means of the deflection memberleg portions extends partially laterally into the respective laterallyaligned recess; and in which the predetermined longitudinal limits ofeach of the recesses provide a predetermined clearance for therespective connection means partially received therein in bothlongitudinal directions to provide clearance for the predeterminedmaximum defiection of the deflection member leg portions resulting froma load on the load receiving means.

12. Scale mechanism including a first generally longitudinal suspensionmember, a second generally longitudinal suspension member spacedlaterally from the first member, the first and second suspension membershaving longitudinally spaced portions, load receiving means operablyconnected to the second member for receiving a longitudinally appliedload, generally lateral substantially parallel strap-like support meansconnected between the first and second member longitudinally spacedportions generally flexible for relative longitudinal movement betweensaid first and second members and generally rigid for absorbing andcancelling out substantially all lateral load components impartedbetween said first and second members by said longitudinally appliedload on said load receiving means, said support means longitudinalflexibility providing said support means incapable of absorbing at leastthe greater portion of any longitudinal load components to which saidfirst and second members are subjected by said load on said loadreceiving means, the support means connected between the first andsecond members at one of said first and second member longitudinallyspaced portions being placed in tension by said load on said loadreceiving means and the support means between the other of said firstand second member longitudinally spaced portions being placed incompression by said load, the first and second members having laterallyopposed inner faces at said support means placed in compression, saidsupport means placed in compression having relatively thin shortflexible sections adjacent said first and second member inner faces andhaving relatively stiff sections of increased thickness the remainder ofand the major portion of the lateral space between said first and secondmembers, a deflection member having longitudinally spaced laterallyextending leg portions joined by a longitudinally extending connectingportion in generally C-shape positioned between the first and secondsuspension members, first connection means mounted extending laterallybetween one of said deflection member spaced leg portions and said firstsuspension member pivotally connecting said one leg portion to saidfirst suspension member, second connection means mounted extendinglaterally between the other of said deflection member spaced legportions and said second suspension member pivotally connecting saidother leg portion to said second suspension member, the first and secondconnection means being operably connected to the respective deflectionmember spaced leg portions at locations laterally spaced from saiddeflection member longitudinally extending connecting portion, thedeflection member absorbing at least the greater portion of alllongitudinal load components to which the first and second members aresubjected by said load on said load receiving means and the absorptionof the longitudinal load components causing deflection of at least oneof said deflection member leg portions, a recess formed in the firstsuspension member having predetermined longitudinal limits in bothlongitudinal directions and being laterally aligned with the secondconnection means connecting a deflection member leg portion to thesecond suspension member, a recess formed in the second suspensionmember having predetermined longitudinal limits in both longitudinaldirections and being laterally aligned with the first connection meansconnecting a deflection member leg por tion to the first suspensionmember, each of the connection means of the deflection member legportions ex- 17 tending partially laterally into the respectivelaterally aligned recess, the predetermined longitudinal limits of eachof the recesses providing a predetermined clearance for the respectiveconnection means partially received therein in both longitudinaldirections providing a predetermined maximum clearance and thereby apredetermined maximum deflection of the deflection member leg portionsresulting from a load on the load receiving means, and means operablyconnected to the deflection References Cited in the file of this patentmember for indicating the deflection between the leg por- 10 2,930,227

tions thereof.

UNITED STATES PATENTS Bemas Oct. 14, 1952 Hohner Mar. 23, 1954 WilliamsAug. 13, 1957 Buckingham Feb. 4, 1958 Hamblin Sept. 2, 1958 Coash et alMar. 17, 1959 Spademan et al Mar. 29, 1960

